Generally, a known combustion burner for producing combustion gas is provided with a swirler for swirling air. For instance, a gas turbine including a compressor, a combustor provided with a combustion burner, and a turbine, is equipped with a pilot burner and a main combustion burner (premixing combustion burner) serving as combustion burners, and a swirler is disposed in an air flow passage of such a combustion burner.
Patent Document 1 discloses a combustion burner provided with a plurality of swirl vanes arranged in a radial fashion in an air passage around a combustion nozzle. Patent Document 1 also discloses a configuration with a partition wall for dividing the air passage into air passages on the inner side and the outer side in the radial direction. With this configuration, a layer of air (film layer) having passed through the air passage on the inner side in the radial direction covers a downstream end portion of the combustion nozzle, and thereby it is possible to suppress a temperature increase of the downstream end portion.
Further, Patent Document 2 discloses a burner including: a partition wall partitioning an air passage region at the inner side from an air passage region at the outer side in the radial direction; and swirl vanes disposed in the air passage region at the outer side in the radial direction. With the above burner, air is not swirled in the air passage region at the inner side in the radial direction, and thereby the axial-flow velocity is increased at the inner side.